telstra business trying to sell advertising

I called back number (07) 4526 7289 reached IVR for a company called Telstra.

Says they are from Telstra Business Centre wanting to speak to the business owner in regards to cybersecurity. Says he wants to "bring a few things to their attention"
When i asked for details to return the call, he provided a different contact number to call back

Called, I called back, no company name, message said we are experiencing long waitlists, please be patient but who are they ?

Multiple calls received from this number. They did not leave a message

Caller: (07) 4526 7289

This is a Toowoomba QLD number but female caller said she was calling from Telstra Business at the Gold Coast. When I looked up number afterwards it said it was SingTel by Optus.
She asked was I happy with the business services? I told her I stopped working for the company she mentioned in December 2020. I advised that I removed my phone number from business account. She was going to email me in case I wanted to discuss any further business but she ended call before I could give details. Just as well, I wasn’t going to provide them.

Caller: (07) 4526 7289

Got a call from this number and they did not leave a message so how could I know who to ask for when I called back.

Calls but don't leave message